Recovery of methyl ethyl ketone



1958 o. v. LUKE, JR., ETAL 2,862,853

RECOVERY OF METHYL ETHYL KETONE I I Filed June 3, 1954- 6 rays 2 M4719? United States Patent ancovanr or METHYL ETHYL KETONE (Bren V. Luke, J12, Summit, N. J., and George B. Ulvild, Robstown, and James S. MaeKenzie, Corpus Christi, Tex., assignors to Celanese Corporation of America, New York, N. Y., a corporation of Delaware Application June 3, 1954, Serial No. 434,326

1 Claim. (Cl. 20239.5)

This invention relates to the recovery of methyl ethyl ketone and relates more particularly to a process for the recovery of methyl ethyl ketone from a mixture containing, in addition to the methyl ethyl ketone, lower aliphatic alcohols and esters of lower aliphatic alcohols with lower aliphatic acids, which mixture may also contain lower aliphatic ketones.

By the oxidation, in the liquid phase, of lower aliphatic hydrocarbons it is possible to produce a large number of oxygenated compounds. Such compounds are obtained in the form of a complex mixture from which it is necessary to separate the individual compounds for commercial use. It is possible to eifect a partial separation of the compounds in the mixture by a straight distillation process. However, such a distillation process will not normally resolve the mixture into individual compounds, but will give a series of cuts containing compounds that distill together owing either to the close boiling points of the compounds therein, or to the formation of azeotropes, or both. One such cut comprises a mixture of methyl ethyl ketone, together with lower aliphatic alcohols, such as methanol, ethanol, propanols and butanols and esters of lower aliphatic alcohols with lower aliphtaic acids, such as ethyl acetate and methyl propionate. Such mixture may also contain lower aliphatic ketones, particularly ketones containing five carbon atoms. Since it is not possible to recover methyl ethyl ketone from such mixtures by a simple distillation process, other procedures must be restorted to in order to achieve such recovery.

It is an important object of this invention to provide a process for the recovery of methyl ethyl ketone from such mixtures which will be especially simple and efiicient in operation.

A further object of this invention is to provide a process for the recovery of methyl ethyl ketone from a mixture containing, in addition to the methyl ethyl ketone, lower aliphatic alcohols and esters of lower aliphatic alcohols with lower aliphatic acids, which mixture may also contain lower aliphatic ketones.

Another object of this invention is to provide a process for the recovery of methyl ethyl ketone from a mixture containing, in addition to the methyl ethyl ketone, esters of lower aliphtic alcohols with lower aliphatic acids.

Other objects of this invention will be apparent from the following detailed description and claims,

According to the present invention, it has been discovered that methyl ethyl ketone may be recovered from a mixture containing, in addition to the methyl ethyl ketone, lower aliphatic alcohols and esters of lower aliphatic alcohols with lower aliphatic acids, which mixture may also contain lower aliphatic ketones such as C ketones, by subjecting such mixture to a water extractive distillation whereby a cut containing the methyl ethyl ketone, together with the esters, will pass overhead, leaving behind. the lower aliphatic alcohols and lower aliphatic ketones, and then subjecting the methyl ethyl ketone-ester cut to a second water extractive distillation whereby the esters will pass overhead, leaving behind the methyl ethyl ketone mixed with water. The aqueous methyl ethyl ketone may be used as such or may be treated to remove the water therefrom to obtain a high purity, anhydrous product. Simultaneously with the recovery of the methyl ethyl ketone, the process of this invention also efiects the partial separation of the other compounds in the starting mixture whereby their recov-- tween about 5 and 20% by weight of the lower aliphatic alcohols and between about 10 and 60% by weight of esters of lower aliphatic alcohols with lower aliphatic acids. Such mixture may also contain between about 1 and 5% by weight of lower aliphatic ketones. All the above percentages are on an anhydrous basis.

As the first step in the process, the starting mixture is subjected to a water extractive distillation by introducing the same into a distillation column and also introducing water into the said column at a point above that at which the mixture is introduced. In carrying out this portion of the process, there is preferably introduced into the distillation column from about 1.5 to 4.0 parts by weight of water for each part by weight of the starting mixture and the concentration of water in the liquid phase in the column below the point at which water is introduced is maintained above about 20 weight percent, or preferably between about 25 and 60 weight percent. The distillation column is preferably operated under reflux employing a reflux ratio of between about 4:1 and 10:1. The column head temperature is maintained at between about 72 and 75 C. and there is taken off overhead a mixture of the methyl ethyl ketone and esters. The base of the column is maintained at a temperature of between about and 100 C. and there is removed from the base of the column an aqueous mixture of the lower alipahtic alcohols present in the starting mixture, together with any lower aliphatic ketones that are presen in such starting mixture. The aqueous alcohol mixture removed from the base of the column may be treated further by distillation to recover and purify the alcohols present therein, and the water recovered from such mixketone and esters is introduced into a distillation column and water is also introduced into the said column at a point above that at which the mixture is introduced. For each part by weight of the methyl ethyl ketone-ester mixture there should be introduced into the distillation column from about 10 to 60 parts by weight of water, and the column should be operated to maintain a concentration of above about 70 weight percent of water, or preferably between about 75 and weight percent of water, in the liquid phase in the column below the point at which the water is introduced. The distillation column is preferably operated under reflux employing a reflux Patented Dec. 2,1958

ratio of between about 4:1 and 10:1. The head temperature of the column is maintained at between about 70 and 72 C. and there is taken oif overhead the esters in the methyl ethyl ketone-ester cut. From the base of the column-,which is-rnaintained at a temperature of bet-ween about80 and 100 0, there is taken ofi themethyl ethyl ketone together withwater.

Oneembodiment of our invention is shown diagrammatically in the accompanying drawing.- Referring now more particularly to the drawing, a feed comprising methyl ethyl ketone ('MEK), alcohols and esters is introduced through line. 11' into distillation column 12. Water is introduced into the column 12 through a line 13 at apoint above the plate to which feed is supplied. Vapors of feed are formedin the column and are washed with water, the alcohols being carried down with water and leaving the column at14.

There is distilled off from column 12 the methyl ethyl ketone and esters contained in the feed together with some water. The vapors-leave'through line'15, are liquefied in condenser 16 and a portion is refluxedto column 12 through line 17'. The balance of the condensate is fed through line 18- to a column 19 to which water is supplied through a line 20. The-vapors of methyl ethyl ketone and esters are washed in column 19 and the water carries down the ketone, there being withdrawn from column 19at 21 aqueous methyl ethyl ketone.

Vapors of the estersand some water leave column 19 at 22, are condensed in condenser 23 and partially refluxed through line 24. The balance is withdrawn through line 25.

The following examples are given to illustrate this invention further.

Example I A mixture containing 43.4 weight percent of methyl ethyl ketone, 40.2 weight percent of esters such as ethyl acetate and methyl propionate, 15.8 weight percent of alcohols such as methanol, ethanol, propanols. and butanols, and 0.6 weight percent of other ketones such as C ketones is introduced into a distillation column and there is also introduced into said column at a point above that at which the mixture is introduced 1.75 parts by. weight of water for each part by weight of the mixture .50 that the liquid phase in the column below the said point at which water is introduced contains 25.0 weight percent of water. The column is operated at a reflux ratio of 5 to 1 with a head temperature of 73.5 C. and a base temperature of 88 C. The methyl ethyl ketone and the esters distill overhead, together with some water, and there is taken oil? at the base an aqueous mixture of the alcohols and C ketones. The aqueous alcohols may be distilled from the aqueous solution and the water recovered during such distillation may be returned to the extractive distillation column.

Example I] The methyl ethyl ketone cut produced in Example I which contains 50.4 weight percent of methyl ethyl ketone, 42.0 weight percent of esters and 5.6 weight percent of water, together with traces of alcohols, is introduced into a distillation column and there is also introduced into said column at a point above that at which the mixture is introduced into the column 55.5 parts by weight of water for each part by weight of the methyl ethyl ketone cut so that the liquid phase in the column below the said point at which water is introduced contains 95 weight percent of water. The column is operated at a reflux ratio of 5 to 1 with a head temperature of 7l C. and a base temperature of 97 C. The esters distill overhead, together with some water, and there is taken of at the base methyl ethyl ketone and water.

It is to be understood that the foregoing detailed description is given merely by way of illustration and that many variations may be made therein without departing from the spirit of our invention.

Having described our invention, what we desire to secure by Letters Patent is:

A process for the recovery of methyl ethyl ketone from a mixture containing on an anhydrous basis between about 30 and 60% by weight of methyl ethyl ketone, between about 5 and 20% by weight of lower aliphatic alcohols, and between about 10 and 60% by weight of esters of lower aliphatic alcohols with lower aliphatic acids, which comprises subjecting said mixture to a water extractive distillation by introducing said mixture into a distillation column and introducing water into the distillation column at a point above that at which the mixture is introduced at a rate such that the concentration of water in the liquid phase below the point at which the. water in introduced is between about 25 and 60 weight percent whereby a cut containing the methyl ethyl ketone and the esters will pass overhead during the dis tillation leaving behind the alcohols, and then subjecting the methyl ethyl ketone-ester cut to a second water extractive distillation by introducing said cut into a distillation'column and introducing water into the distillation column at a point above that at which the cut is introduced at a rate such that the concentration of Water in the liquid phase below the point at which the water is introduced is between about and weight percent whereby the esters will pass overhead during the distillation leaving behind the methyl ethyl ketone.

References Cited in the file of this patent UNITED STATES PATENTS 2,607,719 Eliot et al Aug. 19, 1952 

